I suppose the whole 'every person has a DK' thing could have been so that the fans would feel inspired to make their own characters, but I'd like to think that the human world would at least get a solid mention in the story beyond the intro like the characters acknowledging that humans exist.

Honestly, I would also like to have the human/dreamkeeper connection be fleshed out more or even explored in the story a bit. Not to the extent of the characters going to the human world (although I wouldn't mind such a plot point) but at least a bit more of a solid confirmation within the story itself that the Dreamkeepers are indeed linked to humans, and that the nightmares want to destroy/rule both races.

Because the whole human/dreamkeeper connection seems kind of important to the plot itself- its the reason why the Nightmares do what they do, after all. It would seem strange to me to not explore that side of things at least just a little bit. What would be the point of implementing or explaining such an important connection in the story if it just goes unexplored? If thats the case, then there would be no need for a "dream-guardian" sort of set up that we have going on in Dreamkeepers- they could just as easily rename both the Dreamkeeper and Nightmare races and have the conflict take place on let's say... another planet.

So, it would just seem weird to me to not touch upon the human/dreamkeeper connection in the actual story outside of the intro as well. But I have faith in David that he will explain the connection in sort of an abstract and indirect way at least. Meaning, it doesn't have to be as extreme as actually having both realms collide- a bit of exposition would suffice, just to make the connection much more relevant.

All that being said, however, we are only 3, almost 4 books into the series. Perhaps there will be more information on this subject in the later books. Only time will tell.